No prior president has had the markets all atwitter the way Donald Trump has since his election, according to a piece on CNBC.com. His use of Twitter moves markets with just a few keystrokes, and can create volatility especially in individual names, which is something we haven’t seen on this kind of scale in the past.

The story notes President Trump’s tweets about U.S. companies have created unprecedented whipsaw action, even on mega-cap names. It studied 15 stocks cited by Trump more than one time each.

The CNBC analysis found negative tweets produced on average a 1.2% drop in a company’s stock price while a positive tweet boosted shares an average of 1.1% in shares of firms named by Trump. Savvy traders are using Twitter as a public forum on their Bloomberg terminal where headlines make news—and money for those who swiftly take action.

On the down side, CNBC notes, Trump has criticized the likes of Nordstrom, Inc. (JWN​) for its treatment of Ivanka Trump in dumping her product line, and Boeing Co (BA) over the price of Air Force One. He has also taken Merck & Co, Inc. (MRK​) to the woodshed after the pharma giant’s CEO resigned in August from the president's American Manufacturing Council following following Trump’s equivicating response to violence at a rally of white supremacists in Charlottesville, Virginia. (For more, see also: 9 Brands Donald Trump Endorsed on Television.)

The story from CNBC also points out that ExxonMobil (XOM​) got a positive shout out in March when that oil giant elaborated on expansion plans begun in 2013. Trump’s Secretary of State, Rex Tillerson, was the CEO of the oil giant before joining the cabinet. Ford Motor Co. (F) also got a boost from the president that same month when Trump hailed the automakers’ new details from an ongoing plan to invest billions in new plants in the United States.

The president is an equal opportunity offender, as the CNBC analysis notes. He has praised firms that he has previously blasted, including General Motors Co. (GM) — attacked on January 3 for production of the Chevy Cruze in Mexico but on January 24 Trump highlighted a “great meeting with Ford CEO Mark Fields and GM CEO Mary Barra at the White House.” (For more, see also: Is a Boeing, Donald Trump Deal Close?)

These short-term Trump tweet tirades may not have lasting effects, especially since the president has already reversed his position, but the social platform has created a stock market bully pulpit that’s moving money. According to CNBC, positive Trump tweets generated $1 billion in market value for the companies, at least in the near-term; while negative tweets eviscerated $1.3 billion in market value shortly after his digital missives.

Since Trump’s election, the stock market has raced into uncharted territory. It rose 28.5% in the 12 months from Election Day 2016 through November 8. According to Marketwatch, that’s the best post-election gain since the end of World War II.

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